This invention relates to electric lamps having a plastics skirt and, more particularly, to an organic polymer or plastics skirt formed of material capable of withstanding high temperatures and having means for engaging and fixing the plastics skirt to a glass envelope and a metallic base both of the electric lamp.
Plastics skirts are known as a replacement of metallic collars in the lamp art. Replacement plastics skirts provide the means for reducing or even eliminating an arc problem related to metal-to-glass insulated screw bases of lamps. Many lamps, particularly high voltage lamps, operate at high voltage potentials and arcing conditions between the metal base and the metallic and glass insulated collar which are possible failure modes of the lamp. The plastics skirt provides a means to substantially reduce these possible arc problems in addition to reducing any shock hazard of the collar of the lamp. One such plastics skirt is described in a technical article entitled "Lamp Circuitry Collar" by A. Smetana of GE Lighting Business Group of Ohio, published in the May 1983 plastics world magazine.
The plastics skirt of Smetana rigidly affixes to both the glass bulb and to the metallic base of the lamp. The rigid affixation of the plastics skirt of Smetana prevents the skirt from rotating on the bulb during unscrewing. The non-rotation is provided by "staking" which is accomplished by injecting molten solder through two small holes in opposite sides of the plastic skirt and into small depressions in the glass envelope so as to form solder locks. This injection molten solder process forming the solder locks while performing its desired non-rotation of the plastics skirt has disadvantages. The formation of the solder locks is a relatively slow process requiring time for the first solder to set or freeze, then a 180 degree rotation of the skirt and glass to form the second solder lock and then allowing for its related setting time. In addition, the related operation temperature for the solder locks is that of the molten high temperature of solder having a melting temperature of about 495 degrees Fahrenheit.
It is desired that means other than molten solder locks be provided which connects the plastics skirt to both the brass base and the glass bulb and does not have the limitations of the prior art. It is further desired that this means be an integral part of the plastics skirt itself.
Accordingly, an object of the present invention is to provide means formed as an integral part of the plastics skirt so as to rigidly affix the plastics skirt to both the glass envelope and the metal base all of the lamp.